This invention relates to carburetors and, more particularly, to a staged single barrel carburetor.
With the present trend in the automotive industry toward smaller, more fuel efficient automobiles, there is increasing demand for smaller displacement engines to serve as power plants for these vehicles. Thus, the eight cylinder engines that are standard on many of today's automobiles will increasingly give way to four and six cylinder engines. Concurrent with this changeover from larger to smaller engines, there is a need to develop new carburetors for use with the new, smaller engines. The goal is to develop carburetors which promote improved fuel economy and reduced emissions and, at the same time, have good driveability and performance characteristics.
One approach to this problem has been the use of staging techniques, particularly the development of staged two-barrel carburetors. The advantage of a staged two-barrel or staged dual carburetor over a conventional two-barrel carburetor is that the staged two-barrel carburetor is, in effect, two carburetors, i.e., a single barrel carburetor for low speed, low load conditions in which fuel economy and reduced emissions are important and a two-barrel carburetor for high speed, high load conditions in which maximum or near maximum performance is required of the engine on which the carburetor is installed.
While staged dual carburetors help improve fuel economy and reduce emissions, they do have disadvantages. One of these is in the area of driveability. Specifically, there is a problem in that range of driving conditions where staging occurs, that is, when the secondary side of the carburetor comes into use. Prior to this time, fuel is flowing in the primary side of the carburetor, but not in the secondary side. When the transition occurs between one and two-barrel operation, there is a momentary lag in the secondary side operation because of the time needed for fuel to begin flowing in the secondary system. The result is a lag in engine performance which is noticeable to the driver.
Besides this problem, other factors bearing upon future carburetor design are carburetor size, since the carburetor must fit within a smaller engine compartment, weight, since the new smaller automobiles are also intended to be lighter in weight, and cost.